Photographic printing material



Patented 141 rnoroGnArmo rnm'rmd MATERIAL Maximilian Paul Schmidt, Wesbaden-Bicbrlch,

Germany, assignor to Kalle & o. Aktiengesellschaft, Wiesbaden-Biebrlch, Germany "lilo Drawing. Application March so, 1940, Serial I 'No. 321,029. In Germany May 9, 1

'22 Claims. (01. 95-7) The present invention relatesto a process of preparing photographic prints and to light-sensitive layers suitable for said process.

Various processes are already known for, preparing light-sensitive materials by means 'of ferric salts and carbonyl compounds; with the aid of said materials a negative copy may be obtained from a positive. As carbonyl compounds quirrones and nitroso-ketones or isonitroso-ketones have been suggested. For various reasons these light-sensitive materials have not been found useful in practice. A drawback of these products consists in the fact that they cannot be fixed in a satisfactory manner by watering. The picture forming dye-stuffs tend to run on water- Ying owing to an insuflicient stability to water whereby the pictures are strongly reduced in their contrasts or even entirely disappear. Frequently the pictures very strongly fade when being exposed to the action of air. A further drawback consists in the fact that the white of the prints obtained is-often not pure.

Now I have found that excellent prints may be obtained th the aid of light-sensitive ferric salts and keto-compoundsby using ci-iSO-IfltI'OSOQ u-cyano compounds of aryl-methyl-ketones as keto-compounds These compounds may also be.

designated as beta oxo alpha oximino-aryb.

propionic acid nitriles. The compounds correspond to the general formula a-co-c-cn wherein R stands for aryl and x for an isonitroso The arylmay for instance be a phenyl' radical or a naphthyl radical. The aromatic nuclei may carry one or'several substituents. As substituentsfithere' may beapplied halogens, alkyl, groups,,alkoxy groups, nitro-groups or amino.- groups. The amino groups may also carry substituents, for instance alkyl groups or an acetyl group. Alkyl groupshave been found to be es peclally useful as substituents in the aryl nu-.

dleus. For instance monomethyl compounds, dimethyl compounds or trimethyl compounds may be used. A. hydro-aromatic ring may likewise be attached to the aromatic nucleus. The aryl may, therefore, be for instance a tetralin radical or an acenaphthene radical.

The compounds in question together with light-sensitive ferric salts are applied in the form of aqueous solutions into or onto. any desired supports, for instance paper or a film. For this hitherto have served for the preparation of negative blue prints, may be applied. In the first line there may be used the complex water-soluble ferric salts of oxalic acid and citric acid. Besides the potassium ferric oxalates and the corresponding citratesother alkali compounds come into consideration. The term alkali compounds" is here intended to include also ammonium compounds. It is also possible to apply the ferric salts and the cyano compounds separately one after the other to the supports.

Light-sensitive layers may likewise be used, which only contain ferric salts and to which after having been exposed to light the cyano compounds are applied in a suitable form, for

instance in the dissolved condition. The method of producing pictures is similar to the aforenamed known photographic printing process.

The ferric salt is reduced on exposure to light. The ferrous salt produced then'forms together with the'cyano compounds blue to green-colored substances. The pictures may be fixed by merely washing them with water. however, also be fixed by transforming one of the components or both. components into a formin i which they are no longer capable of Y forming dyestuffs when being exposed to light. pictures may, for instance, be fixed by applying an aqueous solution of tartaric acid or citric acid of 10 per cent strength by' means of a roller after they have been exposed to light. 7

For the preparation of the light-sensitive layers the cyano ketones are dissolved in water suitably with addition of alkaline substances, for instance sodium bicarbonate or sodium carbonate and the solutions thus obtained are applied to paper or other suitable supports after the ferric salts have been dissolved in said solutions. If

relatively sparingly soluble cyano-ketones are used it is advisable to add to the solutions lithium carbonate or organic bases, such as triethanol-amine or guanidine. The pH value of the sensitizing solutions advantageously amounts to 6 to 7.5. The solution may also contain additions of colloids, as they are usual in the ferrotype.

process. For instance gum or starch may be added to the solution. An addition of a small quantity of chromic acid saltsv as it is usual'on preparing the known blue print papers is to be recommended. It is sometimes also favorable to add to. the solutions potassium chloride, sodium oxalate, potassium oxalate or sodium metaphosphate because the contrasts of the picture and the stability of the light-sensitive layers may be impurpose a great variety of ferric salts, which proved thereby.

The pictures may,

The-

According to the new process prints are obtained which, in contradistinction to the aforementioned photographic prints prepared in known manner, are distinguished by their good contrasts and their strong shade. The pictures are further distinguished by stability on storing and resistance to water. The stability to the action of alkalies, such as lime or ammonia as well as acids is essentially better than in the case of the iron-pictures produced in known manner. In comparison with the blue print papers now in commerce the new photographic printing materials of the present invention have furthermore the advantage that the pictures produced therewith are immediately present after washing in entire strength so that a treatment with bichro but still absorbent or which has been coated with gelatin. On exposure to light through a positive the dried sensitized paper yields a blue negative picture which is fixed by washing it with water. The print is very resistant to acetic acid and dilute mineral acids, sodium carbonate and dilute caustic soda solution.

(2). .27 grams of w-isonitroso-w-cyano-acetophenone are dissolved in 450 cc. of water, while adding 30 grams of sodium bicarbonate. The solution is adjusted neutral by the addition of a small quantity of dilute acetic. acid. After grams of gum arabic and 54 grams of ferric ammonium citrate have been added the solution is painted on to paper. The dried paper yields, when being exposed to light under a positive 0118-: inal, strong, blue, negative pictures which may be fixed in the normal way.

(3) A neutral solution is prepared from 10 grams of u-isonitroso-u-cyano-4-chloroacetophenone, 7 grams of gum arabic, the quantity of sodium bicarbonate required for the dissolution and 250 cc. of water; grams of ferric ammonium oxalate are dissolved in the solution thus prepared. The solution is painted as usual on to paper. With the aid of the paper sensitized .as described blue prints stable to water may be obtained.

For the preparation of the w-isonitroso-u-cyano-d-chloroacetophenone 18 grams of 4-chlorow-cyano-acetophenone are dissolved in a quantity of glacial acetic acid just sufl'icient for the dissolution. A nitroso-group is introduced into the compound by the addition of 50 cc. of 2 nsodium nitrite solution. The isonitroso compound precipitates on dilution with water. It melts at 129 C. In the same manner there may be obtained from 3-nitro-u-cyano-acetophenone the corresponding isonitroso derivative inc-Q4: 0-C-CN ton I CH: are dissolved in' 100 cc. of water while adding 5 grams of sodium bicarbonate. A solution of 30 grams of ferric ammonium oxalate and .5 gram of potassium bichromate in cc. of water is combined with the first-named solution. By the additionof about .5 gram of ammonium carbonate the mixture is adjusted to a pH value of 6.8, as much as possible with exclusion of light and the solution heated to about 25 C. to 30 C. is applied by painting it to well sized, but still sufficiently absorbent paper. with the aid of the paper thus obtained which is very sensitive to light there are produced, after exposure to light under an original, strong, dark-blue prints which mag be developed by merely washing them with we er.

The w-isonitroso-uj-oyano 2.4 -dimethyl-acetophenone is obtained by introducing a nitroso group into the u-cyano-2A-dimethyl-acetophenone (see Chemisches Zentralblatt", 1930, vol. II, page 3274) in glacial acetic acid. The compound recrystallized from water melts at 154 C.

Similarly valuable light-sensitive layers may be obtained by means of w-isonitroso-u-cyano-4- methyl-acetophenone. This product which melts at 137 C. is prepared in a similar manner as the dimethylated compound from i-methyl-a-cyanoacetophenone (see Chemisches Zentralblatt", 1930, vol. II, page 3274) (5) 1.3 grams of i-u-isonitroso-w-cyano-acetoz-naphthol-methyl-ether OCH:

are dissolved at 30 C. in 25 cc. of water with such a quantity of potassium carbonate that the solution is adjusted to a pH value of 7.5. 3.5 grams of ferric potassium oxalate and .1 gram of sodium meta-phosphate are added to the solution. Wellsized paper is then coated at30' C. with the solution obtained. The paper thus treated is exposed to light under an original and yields blue-green prints which are fixed by washing them with water. Similar pictures may be obtained with the 2-o-isonitroso-u-cyano-aceto -1 methoxy-naphthalene. This compound as sodium salt is rather sparingly soluble; it is, therefore, used in the form of the lithium salt for the preparation of lightsensitive layers. I

For the preparation of l-u-isonitroso-u-cysnoaceto-2-naphthol-methyl-ether the 2-naphtholmethyl-ether is condensed inthe usual manner,

arylmethylketone wherein 1. Photographic printing material consisting of a support which carries a layer comprising a light-sensitive ferric salt and an -isonitrosow-cyano compound of. an arylmethylketone.

2. Photographic printing material consisting of a support which'carries a layer comprising a light-sensitive water soluble complex ferric salt and an w-isonitroso-w-cyano compound of an arylmethylketone.

3. Photographic printing material according to claim 1 wherein the said aryl belongs to the benzene series. v

4. Photographic printing material consisting of a support which carries a layer comprising 'a light-sensitive water soluble complex ferric salt and an w-iSOlIlitl'OSO-w-CYMIO compound of an the said aryl belongs to the benzene series.

5. Photographic printing material consisting of a support which carries a layer comprising a substance selected from the group consisting of the alkali ferric oxalates and the alkali ferric citrates' and an w-isonitroso-w-cyano compound of an arylmethylketone wherein the said aryl be-, longs to the benzene series.

6. Photographic printing material consisting of a support which carries a layer comprising a light-sensitive ferric salt and a, substance of the following formula wherein 'Y stands for an isonitroso group and R for a benzene nucleus which may carry as substituents members of the group consisting of halogen, alkyl group, alkoxy group, nitro group and amino group.

'I. Photographic printing material according to claim 6 in which said ferric salt is a light-sensitive wherein Y stands for an isonitroso group, X for methyl and Z for a member of the group consisting of hydrogen and methyl.

13. Photographic printing material according to claim 12 in which said ferric salt is a lightsensitive water soluble complex ferric salt.

13. Photographic printing material according to claim 12 wherein the said ferric salt is a member of the group consisting of the alkali ferric citrates andthe alkali ferric oxalates.

15. A material of the kind described consisting of a paper support which carries a layer comprising the w-isonitroso-w-cyano-2.4-dimethylacetophenon and ferric ammonium oxalate.

16.-A material of the kind described consisting of a paper support which carries a layer comprising the w-isonltroso-w-cyano-2.4-dlmethylacetophenon and ferric ammonium citrate.

17. A material of the kind described consisting of a paper support which carries a layer comprising the w-isonitroso-w-cyanoirmethyl-acetophenon and ferric ammonium oxalate.

18. An aqueous coating solutionfor the production of photographic printing materials comprising a light-sensitive ferric salt and an misonitroso-w-cyano compound of an arylmethylketone the solution being adjusted to a pH- yalue of 6 to 7.5.

19. An aqueous coating solution as claimed in claim '18 wherein the said aryl belongs to the benzene series.

20. An aqueous coating solution for the pro-.

duction of photographic printing materials comprising a light-sensitve ferric salt and a substance of the following formula wherein Y stands for an isonitroso group and R for a benzene nucleus which may carry as substituents members of the group consisting of halogen, alkyl group, alkoxy group, nitro group and amino group, the solution being adjusted to a pH value of 6 to 7.5.

to claim 9 wherein the said ferric salt is a mem of a support which carries a layer comprising a light-sensitive ferric salt and following formula;

x co-c-cN a substance of the 21. An aqueous'coating solution for the production of photographic printing materials comprising a light-sensitive ferric salt and an 0- isonitroso-w-cyanoacetophenon which carries in the phenyl nucleus at least one methyl group as substituent, the solution being adjusted to a pH value of 6 to 7.5.

22. An aqueous coating solution for the pro duction of photographic printing materials comprising a light-sensitive ferric salt and a substance of the following formula x oo-c-cN MAxnmJAN PAUL scmmr. 

